Method of producing hydrazine

ABSTRACT

GASEOUS NITROGEN IS REDUCED BY REDUCING AGENTS WHICH ARE CHLORIDES OR SULPHATES OF TRIVALENT TITANIUM, BIVALENT CHROMIUM, OR BIVALENT VANADIUM, IN THE MEDIUM OF WATER, METHANOL, ETHANOL, OR A MIXTURE OF SAID SOLVENTS. THE TEMPERATURE OF THE PROCESS IS 20*-100*C., NITROGEN PRESSURE IS 1-150ATM., PH OF THE MEDIUM IS NOT LOWER THAN 8. IN CASE OF USING COMPOUNDS OF THE TWO SAID FIRST METALS AS REDUCING AGENTS, THE PROCESS IS CARRIED OUT IN THE PRESENCE OF MOLYBDENUM PENTACHLORIDE, MOLYBDENUM OXYTRICHLORIDE, SODIUM MOLYBDATE OR POTASSIUM MOLYBDATE. SAID METHOD ENSURES AN INCREASE IN THE YIELD OF THE DESIRED PRODUCT FOR THE REDUCING AGENT EMPLOYED (UP TO 75 MOL. PERCENT) AND ALLOWS THE USE OF REDUCING AGENTS THAT ARE NOT SENSITIVE TO MOISTURE AND EASY TO REGENERATE, AS WELL AS THE USE OF INEXPENSIVE SOLVENTS.

United States Patent M 3,703,354 METHOD OF PRODUCING HYDRAZINE Nikolai Timofeevich Denisov, Oleg Nikolaevich Efimov, Viktor Fedorovich Shuvalov, and Natalia Ivanovna Shuvalova, Moskovskaya Oblast, and Alla Konstantinovna Shilova and Alexandr Evgenievich Shilov, Moscow, U.S.S.R., assignors to Filial Ordena Lenina In- RKhimicheskoi 1 iziki ANSSR, Moskovskaya, No Drawing. Filed Aug. 26, 1970, Ser. No. 67,218 Claims priority, application U.S.S.R., Jan. 12, 1970, 1,387,563 Int. Cl. C01c 1/00 US. Cl. 423-407 7 Claims ABSTRACT OF THE DISCLOSURE Gaseous nitrogen is reduced by reducing agents which are chlorides or sulphates of trivalent titanium, bivalent chromium, or bivalent vanadium, in the medium of water, methanol, ethanol, or a mixture of said solvents. The temperature of the process is 20-1'00 C., nitrogen pressure is 1-15() atm., pH of the medium is not lower than 8. In case of using compounds of the two said first metals as reducing agents, the process is carried out in the presence of molybdenum pentachloride, molybdenum oxytrichloride, sodium molybdate or potassium molybdate. Said method ensures an increase in the yield of the desired product for the reducing agent employed (up to 75 mol. percent) and allows the use of reducing agents that are not sensitive to moisture and easy to regenerate, as well as the use of inexpensive solvents.

The present invention relates to methods of producing hydrazine from gaseous nitrogen. Hydrazine finds an ever wider application in the production of rocket propellants, insecticides, herbicides, plastic materials, medicinal preparations, etc.

In the method practiced in industry for producing hydrazine, the stock materials employed are compounds of bound nitrogen, usually ammonia or urea. Also known in the art is a method of producing hydrazine by reducing gaseous nitrogen in inert solvents, such as ether, 1,1-dimethoxy-ethane, with the use of organometallic compounds in the presence of titanium compounds.

The known industrial method is disadvantageous in that it requires preliminary synthesis of compounds of bound nitrogen, such as ammonia, urea, etc., from gaseous nitrogen. The second of the above-cited methods is disadvantageous in the starting reactants being highly sensitive to moisture, in the use of expensive solvents, in difficulties associated with carrying out the reduction reaction, and in a small yield of the desired product (not over 15 mol. percent) for the reducing agent employed. All these unfavourable factors make the lastmentioned method of producing hydrazine unfit for industrial application.

It is an object of the present invention to provide such a method, which would allow to synthesize hydrazine with the use of such reducing agents that are not sensitive to moisture and are easy to regenerate.

Another object of the invention is to provide such a method, which would allow the use of inexpensive solvents.

Still another object of the invention is to increase the yield of the desired product for the reducing agent employed.

In accordance with the said and other objects, the present invention consists in that gaseous nitrogen is reduced with chlorides or sulphides of trivalent titanium, bivalent chromium, bivalent vanadium. As solvents meth- 3,703,354 Patented Nov. 21, 1972 anol, ethanol or their mixtures are used. The process is carried out at temperatures of 20-100 C. under nitrogen pressure ranging from 1 to 150 atm., in the alkaline medium with pH not lower than 8.

In case of using salts of trivalent titanium and bivalent chromium as reducing agents, the prerequisite additions are compounds of pentavalent or hexavalent molybdenum, such as molybdenum pentachloride, molybdenum oxytrichloride, sodium molybdate, or potassium molybdate.

Said method provides for an increase in the yield of the desired product for the reducing agent employed by as much as mol. percent.

For increasing the yield of hydrazine in case of using chlorides and sulphates of bivalent vanadium, in certain cases it is recommendable to use the above-said compounds of pentaor hexavalent molybdenum.

For ensuring a higher yield of hydrazine, the process is recommendable to be carried out in the presence of magnesium, calcium, barium chlorides or those of trivalent titanium.

The present method of synthesizing hydrazine is efiected as follows. An autoclave is charged with a deaerated solution of a reducing agent, such as chlorides or sulphates of trivalent titanium, bivalent chromium or bivalent vanadium. In case the compounds of the first two abovementioned metals are used as reducing agents, it is required to add to the abovestated solution a solution of molybdenum pentachloride, molybdenum oxytrichloride, sodium molybdate or potassium molybdate. For enhancing the yield of hydrazine in case of using all the said reducing agents, into the reducing solution magnesium, calcium, barium or tetravalent titanium chlorides may be added.

The autoclave is washed with nitrogen, and then a selected nitrogen pressure is set therein. Further the autoclave is heated up to a selected temperature, and then under nitrogen pressure the reducing solution is mixed with the alkaline solution. After a certain period of time the solution is cooled down to room temperature and separated from the precipitated hydroxide by filtration or centrifugation. The resulting solution is assayed spectrophotometrically for the content of hydrazine after acidulation and adding paradimethylaminobenzaldehyde thereinto. Hydrazine may be isolated from the solution by conventional methods, such as evaporation of its salts in an acidulated solution.

Moreover, the present process of producing hydrazine may be effected as follows.

A solution of any of the above cited reducing agents, whereto there may be added magnesium, calcium, barium or tetravalent titanium chlorides is mixed with an alkaline solution in an atmosphere freed from oxygen. The resulting hydroxide suspension is introduced in an autoclave. Further, the process is carried out similarly to the abovedescribed case, but the hydroxide suspension is mixed with the solution of a molybdenum compound under nitrogen pressure.

The hydrazine solution is separated and assayed by following the procedure described in the first-cited case.

The synthesis having been completed, the reducing agent may be regenerated electrochemically, after passing it into solution with addition of an acid.

For a better understanding of the present invention given hereinbelow are illustrative examples of producing hydrazine.

EXAMPLE 1 0.1 ml. of 8- 10* M solution of molybdenum pentachloride in methanol was mixed in air with 0.5 ml. M technical solution of titanium trichloride in 4 N hydrochloric acid and diluted with 1 ml. of methanol. The thus-prepared solution was introduced into an autoclave, whereto 4 ml. of 2 N solution of caustic potash in methanol were also introduced in a separate vessel. The autoclave was freed from oxygen, and the solutions were saturated with nitrogen under a pressure of 100 atm. at a temperature of 20 C. during five minutes. Then under nitrogen pressure the solutions were heated to a temperature of 95 C., blended, and shaken at said temperature during five minutes. Then the nitrogen pressure was relieved, the hydroxide precipitate was separated by centrifugation from the hydrazine solution. The yield of hydrazine was determined spectrophotometrically by reaction with paradimethylaminobenzaldehyde. The yield of hydrazine was 2.710- mol.

EXAMPLE 2 0.3 ml. of 10- M solution of molybdenum oxytrichloride in methanol were mixed with 0.3 ml. of 1 M solution of titanium trichloride obtained by dissolving chemically pure metallic titanium in 6 N hydrochloric acid, and with 0.15 ml. of 1 M solution of magnesium chloride in water. Further the process was carried out by following the procedure described in Example 1. The yield of hydrazine was 610" mol.

EXAMPLE 3 The reaction conditions were the same as specified in Example 2, but instead of magnesium chloride 0.3 ml. of 1 M aqueous solution of calcium chloride were taken. The yield of hydrazine was 210- mol.

EXAMPLE 4 The reactants and the reaction conditions were the same as in Example 1, except for the nitrogen pressure being 10 atm. The yield of hydrazine was 2.7-10 mol.

EXAMPLE 5 The reactants and the reaction conditions were the same as in Example 1, but instead of the molybdenum pentachloride solution use was made of 0.1 ml. of M aqueous solution of sodium molybdate. The yield of hydrazine was 9.6- 10- mol.

EXAMPLE 6 The reactants and the reaction conditions were the same as in Example 1, but a mixture of water and ethanol was used as a medium and the reaction temperature was 40 C. The yield of hydrazine was 1.2-10- mol.

EXAMPLE 7 1 ml. of 10- M solution of molybdenum oxytrichloride in methanol and 5 ml. of a suspension obtained by adding 2.5 ml. of 1 N alkaline solution to 2.5 ml. of 0.4 M solution of chromium chloride containing 1-10- mole of magnesium chloride, were mixed or blended in an autoclave under nitrogen pressure of 100 atm. at a temperature of 84 C. The reaction was run during minutes. The hydrazine solution was separated from the precipitate and assayed by following the procedure described in Example 1. The yield of hydrazine was 1.5- 10 mol.

EXAMPLE 8 The same reactants were used as in Example 7. The reaction temperature was C., pressure, 100 atm., and time, 12 hours. The yield of hydrazine was 3.7- 10-' mol.

EXAMPLE 9 0.5 ml. of 0.25 M solution of bivalent vanadium sulphate in a mixture consisting of 30 percent Water and 70 percent methanol, and 0.2 ml. of 2 M aqueous solution of magnesium chloride were mixed under nitrogen pressure of 120 atm. at a temperature of 60 C. with 5 ml. of 2 N solution of caustic potash. The reaction time was 15 minutes. The separation of the hydrazine solution from the precipitate and the assaying were carried out as described in Example 1. The yield of hydrazine was 2.2-10- mol.

EXAMPLE 10 The reaction conditions and the reactants were the same as in Example 9, except for the nitrogen pressure of atm. The yield of hydrazine was 1-10 mol.

EXAMPLE 1 1 1 ml. of 0.06 M solution of bivalent vanadium sulphate in a mixture-consisting of 35 percent water and percent methanol, and 0.5 ml. of 0.5 M solution of magnesium chloride in methanol were mixed under nitrogen pressure of 120 atm. 'at a temperature of 20 C. with 6 ml. of 6 M solution of caustic potash in methanol. The reaction time was 45 seconds. The yield of hydrazine was 1-10- mol.

EXAMPLE 12 A suspension comprising 4.5-10- mole of bivalent vanadium sulphate and 4.5 10- mole of magnesium chloride in 0.6 N methanol solution of caustic potash was mixed with 2 ml. of 2-10 M solution of molybdenum pentachloride in a mixture consisting of 39 percent water and percent methanol under nitrogen pressure of 100 atm. at a temperature of 70 C. The reaction time was 15 minutes. The separation of the hydrazine solution and assaying were carried out as described in Example 1. The yield of hydrazine was 1.8-10 mol.

EXAMPLE 13 0.3 ml. of 0.8 M titanium chloride solution prepared by dissolving chemically pure metallic titanium in 6 N hydrochloric acid were mixed with 0.3 ml. of 0.4 M aqueous barium chloride and with 0.1 ml. of 3-10- M methanol solution of molybdenum oxytrichloride. The solutions thus prepared were introduced into an autoclave, whereto in a separate vessel 4 ml. of 2 N alcoholic solution of alkali was introduced. The temperature was C., and nitrogen pressure, atm. The reaction time was 10 minutes. The hydrazine Was assayed as described in Example l. The yield of hydrazine was 2.56-10- mol.

EXAMPLE 14 The reaction conditions and the amounts of reactants were the same as described in Example 13 with the exception that instead of barium chloride 0.3 ml. of 0.4 M aqueous solution of titanium tetrachloride were taken. The yield of hydrazine was 2.74- 10* mol.

What is claimed is:

1. A method of producing hydrazine which comprises reducing gaseous nitrogen in the presence of a reducing agent selected from the group consisting of chlorides and sulphates of trivalent titanium and bivalent chromium, the reduction being carried out in a solvent selected from the group consisting of Water, methanol, ethanol and a mixture of water with one of the alcohols, at a temperature of 20 to 100 C., a nitrogen pressure of 1 to atmospheres, the pH of the solution being no lower than 8, in the presence of a compound selected from the group consistmg of molybdenum pentachloride, molybdenum oxytrichloride, sodium molybdate and potassium molybdate, the molar ratio of the reducing agent and molybdenum compound ranging from 10 :1 to 10 :1.

2. A method as claimed in claim 1, wherein the reductron process is efiected in the presence of magnesium chloride.

3. A method as claimed in claim 1, wherein the reductron process is effected in the presence of calcium chloride.

4. A method as claimed in claim 1, wherein the re- (l lCtlOn process is efiected in the presence of barium chlor1 e.

5. A method as claimed in claim 1, wherein the reduction process is effected in the presence of tetravalent titanium chloride.

6. A method of producing hydrazine which comprises 7. A method as claimed in claim 6 wherein the rereducing gaseous nitrogen in the presence of a reducing duction process is carried out in the presence of molybagent selected from the group consisting of chlorides and denum pentachloride. sulphates of bivalent vanadium, the reduction being carried out in a solvent selected from the group consisting of 5 References Cited water, methanol, ethanol and a mixture of water with one FOREIGN PATENTS of the alcohols, at a temperature of 20 to 100 C., a nitrogen pressure of 1 to 150 atmospheres, the pH of the 966,320 10/1950 France 23 190 solution being no lower than 8, in the presence of magnesium chloride, the molar ratio of the reducing agent 1 OSCAR VERTIZ Pnmary Exammer and magnesium chloride ranging from 1:1 to 1:4. 0 H. S. MILLER, Assistant Examiner 

8. IN CASE OF USING COMPOUNDS OF THE TWO SAID FIRST METALS AS REDUCING AGENTS, THE PROCESS IS CARRIED OUT IN THE PRESENCE OF MOLYBDENUM PENTACHLORIDE, MOLYBDENUM OXYTRICHLORIDE, SODIUM MOLYBDATE OR POTASSIUM MOLYBDATE. SAID METHOD ENSURES AN INCREASE IN THE YIELD OF THE DESIRED PRODUCT FOR THE REDUCING AGENT EMPLOYED (UP TO 75 MOL. PERCENT) AND ALLOWS THE USE OF REDUCING AGENTS THAT ARE NOT SENSITIVE TO MOISTURE AND EASY TO REGENERATE, AS WELL AS THE USE OF INEXPENSIVE SOLVENTS. 